Centrifugal switching device.



E. MATTMAN.

CENTRIFUGAL SWITCHING DEVlCE.

APPLICATION men MAY 21. 1912..

1,236,733. Patented Aug. 14,1917.

WITNESSES: Z mxzlgX/ENTOR ATTORNEY UNITED STATES: PATENT OFFICE.

EMIL MATTMAN, OF WILKINSBURG, PENNSYLVANIA, AS$IGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CENTRIIEUGAL SWITCHING DEVICE.

Specification of Letters Patent.

Patented Aug. 14, 1917.

Application filed May 27, 1912. Serial No. 700,025.

To all whom it may concern:

Be it known that I, EMIL MATTMAN, a cltizen of and a resident of Wilkinsburg, in the county of Allegheny and Stateof Pennsylvania, have invented a new and useful Improvement in Centrifugal Switching Devices, of which the following is a specification.

My invention relates to switching devices, and it has particular reference to centrifugal speed-limit devices such as are employed in connection with rotary converters and other dynamo-electric machines for the purpose of automatically preventing excessive speeds.

The object of my invention is to provide a device of the above-indicated character that shall be simple, inexpensive and durable inv construction, effective and reliable in operation, and particularly adapted to efiect a positive operation of the switching device with which it is associated.

It has been customary to employ devices of this general class for the purpose hereinbefore mentioned, but such devices have usually been constructed and have operated in substantially the manner of engine shaft governors which are adapted for speed regulation and in which the pivotally mounted member is gradually moved from its inner to its outer position in accordance with variations in speed. Thus, the switching devices have not been actuated positively and their operation has been more or less unreliable for the reason that successive light blows are delivered to the tripping members of the switching devices prior to their final release.

According to my present invention, I provide a speed limit means having a tripping device which is adapted to fulfil the objects hereinbefore mentioned and to operate with uniformity and positiveness. Furthermore, the device is so constructed that the movement of the pivotally mounted arm, which depends for its actuation upon centrifugal force, is rapid, and the arm moves quickly from its inner initial position to its outer position, whereby a single and positive blow is delivered to the tripping member of the switching device.

In t e a c mp yi g draw ng, Fig 1 is an end view, in elevation, of a switching device constructed in accordance with my invention. Fig. 2 is a view, in side elevation, and Fig. 8, is a view, partially in section and partially in side elevation, of the tripping portion of the device shown in Fig. 1.

Referring to the drawing, the apparatus here shown comprises a tripping device 1 and a switching device 2, said tripping device being fixed to a rotatable member or shaft 3 and comprising a main body member 4, a pivotally mounted weighted arm 5, and a spring 6, while the switching device 2 is disposed in cooperative relation to the tripping device 1 and comprises a casing or box 7, a movable switch member 8, a spring 9, and a plurality of stationary contact terminals 10.

The body member 4 is substantially cylindrical in form, being provided with an integral peripheral flange 11 having a plurality of openings 12, 18 and 14 for purposes to be hereinafter pointed out. The movable member 5 is conveniently of horseshoe shape, one end 15 thereof being pivotally secured to the main body member 1 by means of a stud 16, while a weighted striking portion 17 is integrally associated with said member and disposed substantially midway between its respective ends. The free end 18 of the pivotally mounted member 5 is located on the same side of the shaft 3 at its pivoted end 15. One end of the tension spring 6 is secured to the free end 18 of the arm 5 and the opposite end thereof is attached to an adjustable member 20 that is located adjacent to the pivotal support 16. The arrangement of parts is such that the horse-shoe shaped movable member 5 partially surrounds the shaft 3, and the spring 6 is so disposed that it acts upon the free end 18 of movable member 5 in a direction that is substantially at right angles to the direction of movement of that portion to which it is attached.

The adjustable member 20 is of L-shape and is provided with an arm 21 that pro jects, and is movable, in an opening provided in a boss 22 which forms an integral part of the main body member 4. The opening just referred to is threaded to receive an adjustable set nut 23 by means of which the member 20 may be moved in order to secure any desired amount of tension in the spring 6. For convenience in construction, the arm 21 is preferably cylindrical in form and hence the member 20 is provided with a pin 24 which is adapted to project into and coiiperate with a slot 25 provided in the body member 4 for the purpose of preventing a rotative movement of the member 20, and maintaining the same in its proper position.

The openings 12 and 14 in the peripheral flange 11, permit the members 6, 20 and 23 to be readily inserted and adjusted in position, while the opening 13 is provided for the purpose of allowing an unrestricted movement of the member 5 during its operation.

The casing or box 7 of the switching device 2 may be suitably secured to a projecting lug 27 which may constitute a part of a supporting hearing or pedestal 28 by means of which the shaft 3 is supported in position. The switch member 8 is pivotally mounted, intermediate its ends, upon a bracket portion 29 that is provided upon the casing 7 and said switch member 8 embodies an upwardly projecting pawl or dog 30 which normally is located adjacent to the tripping device 1 and in such a relation thereto that it is engaged by means of the striking portion 17 when said portion occupies its outer position. The lower end 31 of the switch member 8 is provided with suitably insulated movable contact member 32 which is adapted to coiiperatively engage the stationary contact terminals 10 when the switching device 2 is closed. The contact terminals 10 are suitably mounted upon an insulating block 33 and are provided with a plurality of electrical conductors 34 in the usual manner.

The spring 9 is connected between the end of a bracket member 35, forming a part of the casing 7, and the pawl or dog 30, and is so disposed with respect to the pivotal support 36 for the switch member 8, that said switch member is normally maintained in its open position, but, when released and carried across its dead center position, is positively actuated by means of thespring 9. A set screw 37 is provided in the casing 7 to codperatively engage the lower end 31 of the switch member 8 when said switch member occupies its open position. It will be understood that, by suitably adjusting the set screw 37, the relationship of the spring 9 to its pivotal support 36 may be changed, whereby adjustments in the amount of force necessary to release the switch member 8 may be effected.

Assuming the various parts of the de vice to occupy the positions shown, and the rotational speed of the shaft 3 to be increasing, the operation of the device is as follows:

Below the speed for which the device is adjusted, the tension of the spring 6 is sufficient to overcome the centrifugal force acting upon the weighted arm 5, and said arm is, therefore, maintained in its initial inner position. However, when the speed is increased to such an extent that the centrifugal force on the movable arm 5 causes a torque about the pivotal support 16 that is greater than that which is effected by means of the spring 6, the member 5 is moved into its outer position.

By reason of the peculiar construction and arrangement and location of parts, no intermediate position can be maintained, as only a comparatively slight elongation of the spring 6 is permitted, so that, after the centrifugal force once predominates over the action of the spring 6, it increases faster than the opposing tension of the spring. Hence, the arm 5, when once moved, is thrown quickly to its outer position. Another advantage of disposing the parts in such a manner that the spring 6 is elongated but slightly is that a uniformity of operation may be secured by reason of the fact that the spring 6 is not subjected to excessive distortions and is not worked beyond its elastic limit.

lVhen the striking member 17 occupies its outer position, it is brought into engagement with the upper end of the pawl or dog 30 and the switch member 8 is thereby forced across its dead center position after which the spring 9 serves to actuate the switch member and cause a quick and positive engagement of the coiiperating contact members 10 and 32.

When the speed of the shaft 3 is decreased sufliciently for the action of the spring 6 to predominate over the centrifugal force acting upon the movable member 5, said member is drawn into its inner initial position. The switching device 2 may be reset manually by merely forcing the dog 30 to its inner position without necessitating the removal of the cover (not shown) of the casing of box 7.

I have shown and described a switching device embodying specific structural details, but those skilled in the art will readily understand that various modifications may be effected therein without departing from the spirit and scope of my invention, and I desire that only such limitations shall be imposed as are indicated in the appended claim.

I claim as my invention:

A centrifugal device comprising a. ro-

tatable member, a pivotally mounted arm associated therewith and having its respective ends located on the same side of said rotatable member, a weighted striking portion disposed substantially midway between said ends, an adjustable member adjacent to the pivotal support of said arm and in slotted engagement with said rotatable member, and a tension spring connected between said adjustable member and the free 10 end of said arm.

In testimony whereof, I have hereunto subscribed my name this 23rd day of May,

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

